Inert heat material in contact mass catalysis



uly 15, 1947' E. J., HouD'RY INERT HEAT MATERIAL IN CONTACT MASSGATALYSIS Filed April 1'7, 1942 2 Sheets-Sheet 1 2' area INVENTOR 50mgl/WORY July, .15, 1947. E.- J. HOUDRY LNERT HEAT MATERIAL IN CONTACTMASS CATALYSIS 2 Sheets-Sheet 2 Filed April 17, 1942 gus . lime/mm.-426cm: .1 haupen A, Wraps/var:

Patented July 15, 1947 UNITED- STATES PATENT v OFFICE INERT HEATMATERIAL IN CONTACT MASS CATALYSIS v Eugene J. Houdry, Ardmore, Pa,assignor to P Houdry Process Corporation, Wilmington, Del., 7 v p acorporation of Delaware Application April 17', 1942, Serial No. 439,338

'tact masses for promoting, controlling or in any Claims. (01.260-080)manner assisting in the direction and extent of organic .reactions.

One object is to simplify and to improve catalytic operations andapparatus. Another object is to pnovide novel forms otcontact masses.

Other obiects will be apparent from the detailed description whichfollows.

The invention involves simplification and cheapening of apparatusiorconducting catalytic operations on a commercial scale. It furtherprovides for operating the same on an adiabatic basis by utilizing theapparatus for successive reactions which complement one another so thatthe contact mass is continuously maintainedwithin a temperature rangesuitable for the. reactions without requiring an extraneous heating orcooling fluid to be circulated through or around the reaction chamber.The contact mass is made up of active and inactive partsln uniformdistribution withinthe contact or reaction chamber. An importantcharacteristic of the mass is its high specific heat per volume of masswhich enables the mass to absorb or to store up heat which can besubsequently released as desired or required.

In preparing to conduct a catalytic operation in a cycle of alternatingon-stream and regencrating reactions without the aid or an extraneousfluid to remove heat or to supply heat, the first essential is todetermine how the material to be charged to the operation cracks ordehydrogenates under a series'of diflering temperatures.

Withthis information the desired mean temperature or operating range oftemperatures for the on-stream reaction is selected. The contact'mass isthen selected, due consideration being given to thejheat of reaction andto the quantity of coke deposit pervolume of contact mass needed toproduce the proper quantity of heat during regeneration. In general theratio of active catalyst' to inactive heat absorbing material will be inthe range of 1:3 to 3:2, depending upon the specific heat and the weightof the inactive material as compared with the samecharacteristics oi theactive catalytic material. Any known or suitable catalysts may beutilized. For cracking operations silicious catalysts are suitable, suchas blends orcompounds of silica and alumina, of natural or artificialorigin, with or without the inclusion of other active components such asmetals or metallic compounds, etc. For dehydrogenation operations theusual dehydrogenating catalysts such as chromium, molybdenum, vanaheator the active and inactive materials may be combined in units which makeup the contact mass.

Among the commercial materials which are suitable for heat absorptionare the following:

Heat capacity s cm expressed as be c gram-ca ories Density Heat perliter(solid) per. deg. 0.

Iron (metal) 7. 7 0. 17 l, 310 Fused alumina (Trade names- Aloxite, Alun3. 0. 31 1, 250 Magnesite Brick 3. 6 0. 31 1,070 Dead Burned Magnesite0r 3. 1. 0.31 950 Chrome brick 3. 95 0.29 1, Silica brick g 2. 35 0. 327 Fireclay brick 2. 6 0. 26 080 Ganister (Quartz) 2.6 0. 31 800Additional materials of difiering heat capacities are readily prepared,it needed, of which'the following may serve as examples: 1

Heat capacity expressed as Heat Treatment cific gramc'ilones sity Heatper liter (solid) per deg.C.

1 40%Bentonite, 1400'F.ior?l1rs ,l.7 0.26 440 607 Kaolin. p 2 20%lentonite, do 1.64 0.26 425 807 Kaolin. i 3 10%l entonite, do 2.33 0.21490 40% Kaolin, I y 50% iron. 4 10% entonite, do 2.13 0.25 530 40%Kaolin, I 50% Fe -,O4.

Th heat capacities listed above 'are at 540 C. (1000 F.) and are thetrue measure of comparison between materials since they express theamount of heat 'storedin a unit volume" of'the In someinstances'thematerials uti-. lized for heat"storag'e will not beentirely inert I material.

' catalytically and will in'some degree either im-,

prove or impair the reaction. It is also expedient at times toincorporate'inthe catalytic portion of the contact m ass,or in theinert"portion,"or in both portions, a small quantity of metal'ormetallic compound, as of manganese, nickel, copper, cobalt, chromium,iron, etc., to serve as an oxidation promoter thereby to insure morerapid and complete burning of coky deposits during on an enlarged scalethrough genating and cracking operations to produce lighter hydrocarbonssuch as motor fuel, aviation fuel, etc., from heavier hydrocarbons canbe effected in the range of 850 to 975 F. or with a mean temperature ofabout 925 dehydrogenating or cracking operations, as to produce gases,especially oi the unsaturated or olefinic type, can be conducted in therangeof 975 to 1075 F. (mean temperature about 1025 F.) or even higheras in the range of 1075 to 1175" F. (mean temperature about 1125 F.,etc.)

The accompanying drawings indicate typical forms of appai atus andmethods of operation in accordance with the present invention. In thedrawings Fig. 1 is a vertical sectional view of one type of converter;

Fig. 2 is a similar view showing a modified form of contactmass;

Fig. 3 is a somewhat diagrammatic view of another form of converter withprovision for reversing the flow of reactants therethrough;

Figs. 4 and 5 are graphs with temperature curves illustrating a typicaladiabatic operation under slightly different operating procedures.

Figs. 6 and 7 are perspective views of small quantities of suitablecontact masses;

Figs. 8, 9 and 10 are vertical sectional views individual pieces ofmodified forms of contact masses in which the catalytic material iscombined with the inert or heat absorbing material.

Fig. 11 is a diagrammatic view illustrating in staliation of the processwith provision for operating the catalytic converters either underpressure or under vacuum and with a further provision for the additionof recycle stock to the charge to the process; and

Fig. 12 is a transverse sectional view through the center portion ofFig.2 adjacent one of the plates ofthe heat exchange material.

In Fig. l a very simple and inexpensive form of converter is shown. Itswalls H are constructed of fireclay, firebrick, high temperature cement,or the like for operations at atmospheric pressure. At its upper andlower portions it has valved connections l2 and I3 for the entrance andexit, respectively, of reactants and reaction products. Theseconnections may be constructed, ii desired, of non-metallic material ofthe same general. type as converter walls H, such as tile pipe and thelike. The entire interior of the converter .is the reaction chamber andis filled with contact mass M, which may be in any of the forms shown inFigs. 6 to 10 inclusive. At the bottom of the converter an exit chambersur- I rounds, or partly surrounds, the base of the converter and isseparated from the reaction chamber by grid l4. An alternativearrangement (not shown) is to support the contact mass on a grid abovethe bottom of the, converter so as to leave an exit chamber immediatelybeneath the contact mass. f

F.; more drastic In Fig. 2 a converter similar in all respects to thatshown in 'Fig. 1 is disclosed, but the contact mass M is made up oflayers of active catalytic material a alternating with plates or discsI) of heat absorbing material. In filling the reaction chamber of thisconverter with the contact mass a layer of catalytic material a of, say,/g" thickness is placed at the bottom of the reaction chamber followedby a plate or disc b of inert material of slightly less than thetransverse dimensions of the chamber and of about the same thickness asthe layer of catalytic material it catalyst and heat absorbing materialare to be in approximately 1:1 ratios. Alternate layers of catalyst aand heat absorbing plates b are laid in the chamber until the same isfull. For vertical movement of the reactants through the mass the discsor plates b of heat absorbing material are preferably perforated asindicated in Fig. 12 to permit convenient access of reactants to allparts of the catalyst layers a. When the flow of reactants is arrangedto be in a horizontal-direction or axially of plates b, perforations inthe plates can be omitted.

Fig. 3 illustrates a different form of converter adapted for suborsuperatmospheric pressure of any desired degree and also shows anarrangement for sending reactants through the converter in eitherdirection. The converter comprises a cylindrical metal casing l5, closedat both ends, the interior being provided adjacent its opposite endswith apertured transversepartltions l6 and l'l, which divide theconverter into a central reaction chamber to receive the contact massand end manifolding chambers l8 and IS. The entire exterior of theconverter is enclosed by a layer of heat insulating material 20 and theside walls of the reaction chamber are lined with a layer 2| offireclay, firebrick or high temperature cement. -At diagonallyoppositepoints the wall of the converter is apertured and over theseapertures are mounted capped spouts 22 and 23 for filling and emptyingthe reaction chamber with the contact mass. The converter is mounted inan inclined position, approximately 45 to the vertical, to discloseinlet spout 22 and outlet spout 23 at the-highest and lowest pointsrespectively ofthe reaction chamber, after the manner disclosed in mycopending application Serial No. 437,687, filed April 4, 1942, andissued April 15, 1947, as Patent No. 2,418,838. Any of the forms ofcontact mass disclosed in Figs. 6 to 10 may be utilized for thisconverter. It is also possible to conveniently mount in the converter ofFig. 3 contact masses of the type described in connection with Fig. 2,namely, catalytic material in layers alternating with heat absorbingmaterial in the form of plates, grids and the like. The method ofmounting such heat absorbing plates or grids in a converter such asshown in Fi 3, while permitting convenient insertion and removal of thecatalytic part of the contact mass, is disclosed and claimed in myaforesaid copending application in connection with Figs. 4-10 thereof.

The charge to the converter of Fig. 3 is sent to the same by line 24,which has valved branches 124a and 24b communicating with endmanifolding ,of 945 F. is indicated on both broken line.

valved lines 26 or 21. From the opposite manifolding chamber l9 productscan be withdrawn either .byvalved line 28 or valved line 29. Purging ofthe converter from either end, either-by uct lines. The converters'shownin Figs. 1 and 2 can be connected up for reversal of flow of reactantsin a similar manner.

Figs. 4 and 5 indicate by graphs typical opermaterial in dottedsections.

tran section through the mass with flattened or :rounded ends forms theinert portion of the mass ations in accordance withthe inventionfaimedat a mean temperature of approximately 945 F.

with a contact-mass three feet in depth; The temperature scale is on theabscissa and the catalyst depth on the ordinate. g

Fig. 4 indicates the temperatures obtaining when the reactants for boththe'ion-streamand the regenerating periods enter always from the sameend of the converter, the, curve 0 showing the temperatures at the closeof the on-stream period and the curve d th temperatures at the end ofthe regenerating period. Fig. 5. shows the same operation but indicatesthe effect on temperatures when the direction of flow of reactants isreversed at the end of each regenerating period, 1. e. the on-stream andregenerating reactants are sent through the converter in the samedirection for one cycle and then the direction of movement ofreactantsis changed to the opposite direction for the next cycle and soon, the direction of movement being reversed after each regeneratingperiod. The curve e indicates the temperature at the end of anon-vstrearn period and curve 1 the temperatures at the end of aregenerating period. This mode of procedure has the effect of roundingoff the temperature curves and of bringing a greater quantity of thereaction chamber or contact mass into the zone of best operation whichusually extends about 20 to 30 F. on either side of the desired mean oraverage temperature. The mean temperature graphs by the Various-forms ofcontact masses are indicated in the remaining figures of the drawing.Fig. 6 shows the contact mass made up of a mixture 01' separate piecesof catalytic materialand inert material, the catalytic material beingindicated by circles and the inert materialin solid black. Thematerialsmay be made up in piece of the same size or of diflferent sizesbut ior convenience in distinguishing the same and for. separationwhenever the catalytic material needs to be renewed by reason of loss ofactivity or to be changed to promote a different reaction, the catalytic.pieces may for example be of approximately half the size of the piecesof inert material, as for example, 2 mm. pieces of catalyst and 4 mm.pieces of inert material. 9 Fig. 6 shows the inert material'in pieces oflarger size than the active material. In Fig. 7 there is a similarmixture of'inert and catalytic material, but in this instance the inertmaterial takes the form of Raschig rings of metal or porcelain materialin and around which the catalytic material is distributed insubstantially uniform manner and in the proper ratio for control of thereaction.

With this arrangement separation of inert from catalyticmaterial is alsoeasy due to difference in size and shape of the two components of thecontact mass. I g

Figs. 8, 9 and 10 show insection typical forms of contact masses inwhich the catalytic and inert materials are combined in' the individualunits making up the mass, the inert portions being indicated by fullsection lines and the catalytic In Fig. 8 the censomewhat the reverse ofFig. 8 in which the inert 1 material forms an annulus and the catalyticmaterial makes up the central core with rounded end portions. In Fig. 9the inert material is in the general form of jacks used in a child'sgame, over and around which the catalytic material hasbeen molded. *Whencomposite contact units of the forms shown in Figs. 8, 9 and 10 are usedand when the inert material is metal, it will be apparent that parts ofthe metal or inert portion of each of the units will be in contact sothat there will be heat conduction throughout the entire contact masswith a tendency to distribute the heat uniformly throughout the reactionchamber and toapproach a constant temperature throughout the chamber.

A number of examples to illustrate the scope and importance of theinvention are given below:

Example 1 Active: Clay catalyst of moderate activity. Inert: Preparedceramic-apparent density 1made of bentonite and or (2) above. Ratio:Active to inert-6:11. On-stream conditions:

Contact'mass at start-average F 903 Contact mass at endaverage F 840Mean temperature F 871 I Pressure Atmospheric Charging rate litersliquid per hour per liter active catalyst (Total 24) 8 fresh v charge,16 recycle (350-620 F.

boiling range) Steam, by weight ofcharge 50 Time on stream minutes 16Inlet temperature of charge F 825 Regenerating conditions:

. Time of regeneration including purging 5, periods minutes 16 PressureAtmospheric Inlet temperature of regenerating medium F 810 Products:

Gas, 15.5% by weight of of charge specific gravity 1.13 Coke, 5.4% byweight of charge 5.6 grams per liter of catalyst Liquid recovery: 87.8%by volume. v Condensed aviation gasoline: 43.8% by volume. I

The recycle material disappeared in the operation so that there wasnothing left between the kaolin as (1) aviation cut and the 7 bottomswhich had a boiling range of 550-800 1".

Example 2 Contact mass at start-8-verage F 970 Contact mass atend--average- F.. 905 Mean temperature .31... 937 Pressure AtmosphericCharging rate,

liter active catalyst Steam, by weight of charg 50 Time on streamminutes-.. 16 Inlet temperature of charge F 800 Regenerating conditions:

Time of regeneration including purging periods ...minutes 16 PressureAtmospheric Inlet temperature of regenerating me= dium F 800 Theproducts: Percent weightof charge Os. 7 C0,- H2, methane- .64 Y Ethane.59 Propane 2.18

Isobutane .79 I N-butane .08 Iso-butene 1.25 N-butene 2.01 Gasoline(05+) 29.49 Bottoms 3 60.40 Coke 2.40 40 Example 3 Operation: Crackingof naphtha to produce aviaper hour Time-on stream minutes 16 Inlettemperature or charge ..F 820 Regenerating conditions:

' -Time of regeneration including purging periods -..minutes 16 PressureAtmospheric Inlettemperature of regenerating medium ..F 770 TableRecycle Ratio 0 1 2 Charge Rates:

Fresh Feed-Liters per hr. per liter of mass 2] l1 7 Recycle RateLitersper hr. per liter 0! mass 0 11 14 Total Case rate-Liters per hr. per

liter 0! mass 20 22 21 Steam, per cent wt. Fresh Feed 0 0 15 Steam, percent wt. case charge 0 0 5 0n Stream pressures, lbs. per sq. in 12 5 5Yields (Fresh Food Basis):

okep Percentwt 2.0 4.4 6.7 Grams per liter 4. 2 5. 3 5. 1 Debut.Avia.Base275 F. at90%evap.:

Per cent vol 26. 9 29. 4 41; 7 Per cent wt 24. 2 27. 6 39. 7 SyntheticTower Bottoms Per cent Vol 3 33. 4 7. 9 Per cent wt 2 34.3 8. 2 Gm-TotalC4 and Lighter 7 33. 6 45. 0

Isohiitaue:

Per cent vol ll. 4 l3. 5 Per cent wt 8. 2 9. 6 Isobutene:

Per cent voll.. 3.0 4. 0 Per cent 2. 3 3. 0 n-Butene:

Per cent vol 4. 6 6. 8 Per cent wt 3. 6 5. 2 Toluene Content(Initial-300 Cut), vol.

per cent out 9. 62 Product Ins tions:

Debut asoiine- A.P.I 59.5 55.4 53.5 Initial B P 108 110 106 1 134 138132 .50 194 202 216 90% 214 282 282 R. V. P., i 7. 7 7.4 S. T. 79.9 82.8 83.0 G. F. R. Research 88. 9 92. 9 91.0 AFD-l-O Octane Clear 81. lAFD-l-C Octane+3,cc. '1. E. L. 90.5 91.0 92.0 AFD-i-O 0ctane+4 cc. T. E.L- 92. 6 93. 1 94.0 Francis Bromine No 21. 0 31. 6 34. 7 Acid Heat(Calm) 52. 0 68. 0 75. 0 Synthetic Tower Bottoms:

A. P. I 42. 7 Initial B P 306 298 107 320 314 50 7 342 322 90% 394 secE. P 578 Particularly noteworthy'is the 2:1 recycle operation 01' thisexample for the toluene content (almost 10% by volume) of the aviationproduct. Accordingly, such an operation is important as a source ofproduction of toluene as well as of other valuable hydrocarbons.

Example 4 On-stream conditions:

in. gage- (See below) Temperature:

Contact mass at startaverage F 1090 Contact mass at end-- 1 average.."F. 1020 Mean temperature F 1055 Vacuum, inches of mercury 20 Rate:liters of gas at 70 F. per minute per liter of active material 4.75Contact time on total mass in seconds 5.35 Time on stream minutes 20Inlet temperature of gas F 350 Regenerating conditions: Time ofregeneration in minutes including purging periods .'.minutes 20 PressureAtmospheric Inlet temperature of regenerating medium F 1000 Podbielniakanalysis or charge and productsis For continuous operation of theprocess two as follows: converters are needed whenthe on-stream and i ICracked Gas I N-Butanc Charge, 1 1 OnCh argo I 1 v Material on (hackedGas Ch 0n 0 a 1n Crac ed l VIoL' Wtf" Mol Wt. Per cent Per cent. PercentPer cent Percent Calculated Gas Gr 2.01 1.320 Per cent Unsaturates 5.0 T28.3

Example regenerating periods are of the same length as in Operation:Produ tene-2.

Contact mass:

Active: 22.8% CrzOyon cellite. Inert; Prepared materialbentonite" ankaolinas in Example 1. Ratio: Active to inert-1:2.

On-stream conditions:'

Contact mass at start-average F 1190 Contact mass at endaverage F 1165ction of butadiene from bu- Mean temperature F. 1173 Vacuum, inches ofmercury 20 Rate, liters of gas at 70% F. per minute per liter of'activecatalyst 15.5 Contact time on total mass seconds 1.3 Time on streamminutes 5 Inlet temperature of:'gas F n 900 Regenerating conditions:

Time of regeneration including purging periods minutes 10 PressureAtmospheric I n l e t temperature ofregenerating medium 850 Podbielniakanalysis of charge and products is Examples 1 to 4 and three convertersare needed when the regenerating period. is twice as long as theon-stream period as in Example 5. Once the operating conditions havebeen established and the converter brought to temperature with adequateheat storage capacity in the inert portion of the contact mass, thetemperature swing of the mass in the cycles of on-stream andregenerating reactions becomes uniform and regular. Any variations areslight, merely a degree or two per cycle, so that any necessaryadjustment will be infrequent and easily made in any oneoi a number ofdirections, as on entering temperatures of the reactants, on feed rateor rates, composition of reactants, etc. -When production of aromaticsand unsaturates is desired it is often preferable to send both theon-stream and the regenerating reactants into the converter at alltimesfrom the same end so as to havea rising temperature gradient, as in Fig.4, as the onstream reactants traverse the contact mass.

Metals, such as iron and steel, present a high degree of heat capacityper volume of space occupied. The useof such metals evenly distributedthrough the catalyst, as in the form of parallel plates or shot or in'units such as shown in Figs. 8 to 10, gives good temperature controlfor as follows: adiabatic operations. However, the presence oforackedoas Butene-2Cl1g.,

0n Charge I 4 Material" 9 m On On C(sin 1 an a t? Moi. Wt.- M01. Wt. qPercent Percent rercefit Per'ce'nt 0.0 V 0.0 1 1.0 0.0 0.0 0.0 0.0 0.60.8 0.1 13.9 0.0 0.0 1.3 0.4 0.4 0.0 0.0 .0.1 0.1- 0.1 1.0 1.5 v .2 1.11.1 0.0 0.0. I 0.2 0.2 0.2 7.0 7.0 as 7.1 7.0 5.4 5.4 8.5. 0.0 0.4 83.083.6 I 50.0 00.2 05.2 13.1 14.9 14.7

100. 0 7 100.0 100.0 100.0 0&0 100.0

Calculated Gas Gravity 1. 94 1. 66

iron oxide chrome plating,

present invention the on-stream periods are nor-.

mally less than thirty minutes and the reactions are conducted so as toproduce coke deposits not in excess of 15 grams per liter of activecomponent of the contact mass. Usually the coke deposit is considerablylower as between 4 and grams per liter. In dehydrogenating operations,as in Example 5, it is important for best results to operate with cleancatalyst so as to maintain a straight dehydrogenating reaction.Accordingly the operating periods are short and the coke lay down low,as of the order of 1% by weight of the charge, necessitating heat to besupplied during the regenerating period by high temperature air, fluegas, etc.

Certain aspects of the invention disclosed herein comprise subjectmatter of my copending application Serial No. 561,552, filed November 2,1944 as a continuation-in-part hereof.

I claim as my invention:

is detrimental to many reactions. v Hence it is desirable to use alloysresistant to oxidation or to protect the surfaces of such metals 1.Process of effect'ng contacting operations for processing hydrocarbonsin a reaction chamber containing a contact mass subjected to alternatingon-stream and regenerating reactions, the contact mass comprisingcatalvic material and substantially inert heat absorbing material in theratio of at least 1:3, limiting the onstream :periodsto less than thirtyminutes, and adjusting the operating conditions to maintain the contactmass at a predetermined mean temperature in excess of about 850 F.during onstream operations in a continuing cycle by the heat liberatedand absorbed by said mass during th alternating regenerating periods,both the on-stream and the regenerating reactants being fed to andthrough the reaction chamber in the same direction and reversing thedirection of feed after each regeneration.

2. Process of effecting contacting operations on hydrocarbons in areaction chamber containing a contact mass subjected to alternatingonstream and regenerating reactions, the contact masscomprisingcatalytic material and substantially inert heat absorbingmaterial in the ratio of at least 1:3, limiting the on-stream periods toless than thirty minutes, and adjusting the operating conditions tomaintain the contact mass at 'a predetermined mean temperature in excessof about 850 F. during on-stream operations in a continuing cycle by theheat liberated and absorbed by said mass during the alternatingregenerating periods, both the on-stream and the regenerating reactantsbeing fed to said reaction chamber at temperatures below saidpredetermined means temperature and in thesame direction but withreversal of direction after each regeneration.

3. Process of effecting contacting operations on hydrocarbons in anadiabatic cycle of alternating on-stream and regenerating reactions byabsorbing the heat of the regenerating reactions in a contact masscomprising heat absorbing material interspersed with catalytic materialfor promoting the on-stream reactions, the heat absorb- 7 ing materialbeing in suflicient quantity and of suiilcient heat capacity to holdsubstantially the entire mass during on-stream reactions within F. aboveand below a predeterminedmeans temperature, controlling the on-streamoperating conditions to confine the coky deposit onthe contact mass toless than 15 grams per liter of catalytic material, and reversing thdirection of movement of the reactants through the contact mass at theend of a cycle of on-stream and regenerating reactions.

4. Process of dehydrogenatin gaseous hydrocarbons to produce unsaturateswhich comprises subjecting the gaseous charge to the action of a contactmass made up of active dehydrogenating catalytic material and inert heatabsorbing material, said materials being uniformly associated togetherin the ratio of 1:3 to 3:2, operating said mass alternately on streamand in regeneration by oxidation in an adiabatic cycle, effecting theon-stream operation under substantial vacuum and controlling operatingconditions to effect dehydrogenation at a mean temperature of saidcontact mass of at least 100.0 F., both the onstream and theregenerating reactants .being fed to and through the contact mass in thesame direction but with reversal'of the direction of feed after eachregeneratiom 5. Process of convertingbutene into butadiene whichcomprises subjectingthe butene charge to the action of a contact massmade up of active dehydrogenating catalytic material and inert heatabsorbing material, said, materials being uniformly associated togetherin the ratio of 1:3 to 3:2, operating said mass alternately on streamand in regeneration by oxidation in an adiabatic cyclewith reversal ofdirection of feed of reactants aftereach regeneration, maintaining saidmass under partial vacuum during on-stream operations and controllingoperating conditions to effect the conversion at a mean temperature ofsaid contact mass of at least 1150 F.

EUGENE J. HOUDRY.

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